Currently, observation and diagnosis of a body lumen using electron endoscopes is a widely accepted diagnosis method. In such a diagnosis method, since body tissues are directly observed, a lesion is not required to be removed, and the burden on examinees is small. Further, in recent years, other than the so-called video scope, there have been proposed diagnosis devices and ultrasound devices based on various optical principles, and some of such devices have been practically used. As above, new measurement principles have been adopted, and different measurement principles have been combined.
In particular, it is known that information which cannot be obtained by simply seeing an image of a body tissue can be obtained by observing and measuring fluorescence from a body tissue or fluorescence from a fluorescence material applied to a tissue. A fluorescence image endoscope system has been proposed in which a fluorescence image is acquired and displayed with a visible image in an overlapped manner. Such a system serves to an early detection of a malignant tumor, and is therefore very promising.
In addition, methods are known in which a state of a body tissue is determined by acquiring information on the strength of a fluorescence without forming a fluorescence image. In such methods, fluorescence is typically acquired without using an imaging device mounted in an electron endoscope.
Examples of a diagnostic tool for the fluorescence diagnosis, that is, examples of a probe, includes one which enters the body via a forceps channel of an endoscope, and one which is integral with an endoscope.
Generally, such probes include a first optical fiber group that guides light applied to a body tissue and a second optical fiber group that guides light emitted from the body tissue, or includes a fiber group that serves the roles of the first and second optical fiber groups.
A probe has a configuration in which one side (distal end side) thereof to be inserted into the body in such a manner as to face a biological tissue faces the tissue through an optical window member such as a slide glass and an optical device such as a lens. This configuration, however, involves a risk that, when the probe is inserted into the body, the distal end of the probe makes close contact with a biological tissue at the time of irradiating a measurement object part with excitation light, and consequently, the optical window member and the optical device drop off from the probe and remain in the body.
Under such circumstances, a technique has been proposed in which a holding section that holds the optical window member and the optical device from the distal end side of the probe (see, for example, PTL 1). In the technique disclosed in PTL 1, as illustrated in FIG. 19, catch 120 that catches optical device 100 is formed in holding section 110 that holds optical device 100 at the probe distal end side, thereby preventing optical device 100 from dropping off from the probe.
However, such a configuration has the following problem. Specifically, by the thickness of catch 120, space 130 is defined between distal end surface 125 of optical device 100 and a measurement object part of biological tissue 120. Thus, the configuration involves a risk that liquid such as water, blood and bodily fluid on the surface of biological tissue 120 enters space 130, and remains in space 130, for example. When liquid remains in space 130 in this manner, measurement results obtained by the probe may be negatively influenced depending on the kind of the remaining liquid.
In relation to the above-mentioned problem, the techniques disclosed in PTLS 2 and 3 have been proposed. The technique disclosed in PTL 2 is a technique to prevent liquid remaining at an observation window from staying at the side wall end due to the surface tension even when the liquid is evaporated and diffused by supplying air and water from an air-and-water supply nozzle provided at a distal end surface of an endoscope. To be more specific, in a direction of the space of the air-and-water supply nozzle, surface tension fracturing means (for example a plurality of trenches) that fractures the surface tension of liquid emitted by the air-and-water supply nozzle is provided. Thus, it is possible to ensure favorable visibility at the observation window after air and water are supplied.
The technique disclosed in PTL 3 is a technique to effectively remove a foreign matter such as bodily fluid adhered in a film form on the surface of an object lens provided at the distal end surface of an endoscope by jetting cleaning solution such as water onto the surface of an object lens from a water supply nozzle. To be more specific, vibration applying means that applies minute vibration is provided at the distal end portion of the endoscope. This makes it easy to peel from the lens surface the foreign matter adhered in a film form on the surface of the object lens.